1. Field of the Invention
The invention relates to the field of electronic controls for automobiles, and more particularly to the modification of the originally installed and manufactured electronic control modules for internal combustion engines.
2. Description of the Prior Art
Most automobiles have engine functions controlled by onboard computer chips. Air/fuel mixture, timing, temperature and RPM are input into an onboard computer which then calculates the desired engine timing, fuel injection and other control outputs according to a prestored fixed program.
In addition to control of engine parameters, control of anti-theft features, choices of fuel in an alternatively fueled vehicle, and a wide variety of passenger comfort, and safety functions are similarly controlled by onboard computers. In particular, the computer which controls the engine performance is variously referred to as an engine control module, ECM, vehicle control module, VCM, powertrain control module, PCM, or engine control unit, ECU, are used to control the engine, transmission and braking functions among others. For the purposes of this specification all types of electronic control circuits which are used to control the engine will be collectively defined as "engine control modules".
In virtually all engine control modules, an input/output port or means of some type is provided which allows communication between the onboard computer and exterior sources. The input/output port is sometimes referred to as a diagnostic port and is used primarily for engine, powertrain or transmission diagnostics and error detection, or is referenced as emulation port which may be used both for diagnostic purposes and to input various test protocols into the onboard computer for purposes either testing that computer or other automotive systems controlled by the onboard computer.
Regardless of how sophisticated or intelligent the onboard computer system program is, it invariably arises that there are additional functions which should or can be performed, or that the vehicle in certain applications will need to be customized to perform differently than originally intended or designed. For example, most engines and systems are originally devised to burn one type of fuel, such as gasoline or diesel. In certain applications, the same engine can be converted through appropriate conversion of the computer system to burn alternative types of fuel such as propane, compressed natural gas or liquefied natural gas. In fact, the vehicle must be reconfigured in the field, or possibly even when operating, to switch between alternative fuels or various alternative fuels either automatically through sensor feedbacks, preprogrammed feedbacks or through manual control.
What is needed then is a simple system which can be retrofitted to an originally manufactured engine control modules, which are mass produced originally for other purposes and functions. The method must not only be simple and economic, but also must be able to convert the originally manufactured engine control systems without substantial modification or alteration of the original designs.